3-Aminopropanol is used commercially for the production of panthenol and pantothenic acid and is produced by the catalyzed hydrogenation of 3-hydroxypropionitrile.
The most common route to 3-hydroxypropionitrile, the precursor of 3-aminopropanol, is the base catalyzed reaction of acrylonitrile with water. However, two by-product pathways reduce the selectivity of the reaction substantially. One pathway leads to hydrolysis of the nitrile functionality generating acrylamide and, under one set of operating conditions, acrylamide is by far the predominant product. Aside from reducing the selectivity to 3-hydroxypropionitrile, acrylamide is extremely difficult to separate from 3-hydroxypropionitrile as they codistill. At milder reaction conditions the formation of acrylamide is to some degree suppressed. But, a second pathway involves the reaction of 3-hydroxypropionitrile itself with acrylonitrile, thereby resulting in the formation of cyanoethyl ether. To alleviate cyanoethyl ether formation huge excesses of water are necessary to substantially suppress the amount of cyanoethyl ether formed. This, of course, leads to poor reactor productivity and expensive water removal methods.
Another route to 3-aminopropanol via 3-hydroxypropionitrile is through 2-chloroethanol. Sodium cyanide is reacted with 2-chloroethanol to produce 3-hydroxypropionitrile. 2-Chloroethanol and sodium cyanide are both highly toxic substances thereby create operational problems. In addition, 2-chloroethanol is corrosive and requires glass lined equipment.
The major problem associated with the above processes for producing hydroxypropionitrile lies in an inability to control selectivity of the reaction of acrylonitrile with water to enhance production of aminopropanol. Thus, the major obstacle in the 3-aminopropanol production process lies in the manufacture of 3-hydroxypropionitrile precursor. Methods practiced industrially to manufacture 3-hydroxypropionitrile are either chemically non-selective or involve the handling of highly corrosive and hazardous materials.